The blood–brain barrier (BBB) protects the central nervous system from infections or harmful substances¹; its impairment can lead to or exacerbate various diseases of the central nervous system^2,3,4. However, the mechanisms of BBB disruption during infection and inflammatory conditions^5,6 remain poorly defined. Here we find that activation of the pore-forming protein GSDMD by the cytosolic lipopolysaccharide (LPS) sensor caspase-11 (refs. ^7,8,9), but not by TLR4-induced cytokines, mediates BBB breakdown in response to circulating LPS or during LPS-induced sepsis. Mice deficient in the LBP–CD14 LPS transfer and internalization pathway^10,11,12 resist BBB disruption. Single-cell RNA-sequencing analysis reveals that brain endothelial cells (bECs), which express high levels of GSDMD, have a prominent response to circulating LPS. LPS acting on bECs primes Casp11 and Cd14 expression and induces GSDMD-mediated plasma membrane permeabilization and pyroptosis in vitro and in mice. Electron microscopy shows that this features ultrastructural changes in the disrupted BBB, including pyroptotic endothelia, abnormal appearance of tight junctions and vasculature detachment from the basement membrane. Comprehensive mouse genetic analyses, combined with a bEC-targeting adeno-associated virus system, establish that GSDMD activation in bECs underlies BBB disruption by LPS. Delivery of active GSDMD into bECs bypasses LPS stimulation and opens the BBB. In CASP4-humanized mice, Gram-negative Klebsiella pneumoniae infection disrupts the BBB; this is blocked by expression of a GSDMD-neutralizing nanobody in bECs. Our findings outline a mechanism for inflammatory BBB breakdown, and suggest potential therapies for diseases of the central nervous system associated with BBB impairment.

血脑屏障 (BBB) 保护中枢神经系统免受感染或有害物质¹；它的损伤可导致或加剧中枢神经系统的各种疾病^2,3,4。然而，感染和炎症条件下 BBB 破坏的机制^5,6仍不清楚。在这里，我们发现，细胞溶质脂多糖 (LPS) 传感器 caspase-11（参考文献^7,8,9 ）（而不是 TLR4 诱导的细胞因子）激活成孔蛋白 GSDMD ，介导响应循环 LPS 的 BBB 分解或在 LPS 诱导的败血症期间。 LBP-CD14 LPS 转移和内化途径^10,11,12缺陷的小鼠可抵抗 BBB 破坏。单细胞 RNA 测序分析表明，表达高水平 GSDMD 的脑内皮细胞 (bEC) 对循环 LPS 具有显着反应。 LPS 作用于 bEC 引发Casp11和Cd14表达，并在体外和小鼠体内诱导 GSDMD 介导的质膜透化和细胞焦亡。电子显微镜显示，其特征是破坏的血脑屏障的超微结构变化，包括焦亡内皮、紧密连接的异常外观以及脉管系统与基底膜的脱离。全面的小鼠遗传分析，结合靶向 bEC 的腺相关病毒系统，确定 bEC 中的 GSDMD 激活是 LPS 破坏 BBB 的基础。将活性 GSDMD 递送至 bEC 会绕过 LPS 刺激并打开 BBB。在CASP4人源化小鼠中，革兰氏阴性肺炎克雷伯菌感染会破坏 BBB； bEC 中 GSDMD 中和纳米抗体的表达可阻断这一过程。我们的研究结果概述了炎症性 BBB 破坏的机制，并提出了与 BBB 损伤相关的中枢神经系统疾病的潜在疗法。